on the day of the study you arrive at the clinic and confirm your identity. you are asked to confirm that you have fasted as instructed and that you have not taken any prohibited medicines.

the staff records basic vital signs such as blood pressure and heart rate.

a small amount of blood is drawn to establish baseline laboratory values.

the information collected will be used later to compare changes after the study medication is taken.

some participants receive a single oral dose of famotidine 20 mg film‑coated tablet. the tablet is swallowed with water about thirty minutes before the study drug.

famotidine is a medication that reduces stomach acid and is used in this study to help assess the effect of the study drug on the body.

you are given one hard capsule containing either mk‑1403 240 mg or a matching placebo. the capsule is taken orally with a glass of water.

the capsule is a single dose; no additional doses are taken during the study.

after taking the capsule you remain in the clinic for a period of observation. during this time a series of blood samples are collected to measure the amount of mk‑1403 in the bloodstream.

the timing of the samples follows a schedule defined by the study protocol, covering the early period after dosing and later time points up to at least 24 hours.

once the last required blood sample is taken, vital signs are checked again.

you receive written instructions on what symptoms to watch for and how to report any possible adverse event.

a follow‑up visit or telephone contact is scheduled a few days after the study day to ask about any delayed symptoms or side effects.

the follow‑up ensures that any late‑occurring adverse events are recorded.